Re: importing functions from image package to core

[Carnë Draug]

On 15 October 2012 21:01, John W. Eaton <address@hidden> wrote:
> On 15-Oct-2012, Carnë Draug wrote:
>
> | Hi
> |
> | there's a bunch of simple functions on the image package that I think
> | could be moved to octave core (even though they used to belong to the
> | matlab image processing toolbox). These are the isbw, isgray, isind
> | and isrgb.
> |
> | The reason I propose the move is that some functions in core already
> | perform this checks but have their own code.
>
> Which functions do that?

cmpermute, gray2ind, ind2rgb, rgb2hsv, rgb2ind and rgb2ntsc. Their
checks are not exactly the same but does this come from design or
because they were written by different people at different times? They
are usually split into separate parts so the error message says
exactly why it's not a RGB or indexed image instead of just saying
that it's not one.

> | This functions are very
> | simple and would cause very little maintenance issues while reducing
> | repeated code.
> |
> | If no one objects, I can prepare a changeset with them.
> |
> | By the way, matlab removed this functions because of
> | 
> http://blogs.mathworks.com/steve/2007/03/09/what-happened-to-isgray-isind-isbw-and-isrgb/
> | Not sure about the best approach there.
>
> It seems like these functions are not really very useful.  So why
> should we have them?  I'd vote for deprecating them instead of moving
> them to core Octave.

Because pretty much every function on the image packages uses them for
input check. On top of them there's also a private one, isimage, that
simply checks if it's a matrix, not empty, not sparse, and real. Or do
you mean all of them should be made private?

Carnë